data centers in the u.s. account for one-quarter to one-third of that, the estimates show. you quote peter gross, a single data center can take more power than a medium-sized town. >> that is right. that work that you mentioned on the electricity usage was done by a researcher at stanford. and the center for dynamics, a london firm. some people ask, is that energy being used all or part of the time. once a data center turns on, it has a steady load. it is always, day or night, whether august, september, january -- they're trying that amount of electricity worldwide according to the best estimates from the best people in the field. >> why does it work the way? >> in part, it is because of the way that this field has grown from a few computers in someone's dorm room or back office, now to these gigantic facilities which so musmuch business depends, and where consumers expect the services to be ready at the touch of a button or a tap on the screen, they have gotten to the point where they turn them on and leave the month. that is why the figure is both so high, but also so con